1. Field of the Invention
This invention relates to medical endoscopes and, more particularly, to a system for reducing drag on the movement of an electrode in a resectoscope and a method of making the same.
2. Prior Art
A typical resectoscope for transurethral resection consists of four main elements. The first element is a rigid endoscope or telescope for observing the interior of the human bladder, or operative sites near the base of the urethra. The endoscope comprises an objective lens and a series of relay lenses housed within an endoscope barrel or stem, the stem being connected to an eyepiece housing containing suitable lenses for proper magnification. The second element takes the form of a handle assembly commonly referred to as a working element. The working element serves as the means for connecting electrosurgical current from an electrosurgical generator to the third element, an electrode assembly. The working element is also capable of slidably moving the electrode assembly axially, such axial movement being observable through the eyepiece of the endoscope. The combination of the endoscope, working element, and electrode assembly is locked into a fourth element, a resectoscope sheath. The sheath consists of a tube and a union body and lock assembly. In an operative procedure the sheath is placed into the urethra prior to introduction of the other elements.
The electrode assembly is removably connected to a guide block of the working element. The guide block is movable such as by a rack and pinion mechanism or by an operator deflecting a spring to advance or retract the electrode assembly. The guide blocks in the prior art generally are mounted on one or more guide bars of the working element. The guide bars have been known to be either circular or square in cross-section with guide bar apertures in the guide block also being matingly circular or square in cross-sectional shape, respectively. The guide block is thus slidingly mounted on the guide bar or bars. Lubrication is generally provided by the guide block by having the block comprised of Teflon, a trademark of E.I. Dupont Co., or a similar material. Prior art resectoscope working elements, in addition to a telescope sheath, generally also have an electrode assembly sheath. The electrode assembly is generally slidably connected to either the telescope and/or an electrode guide of the working element. The electrode sheaths have generally been known to be of two types; a substantially enclosed tube or a partial tube with a longitudinal slot along its entire length. The longitudinally slotted electrode sheaths, however, can only use an electrode assembly with a rigid outer sleeve along substantially its entire lead because of the lack of rigidity in the slotted electrode sheath. The substantially enclosed tube electrode sheaths provide sufficient rigidity such that electrode assemblies without rigid outer sleeves or with flexible leads can be used therein.
However, problems have arisen in the devices known in the prior art. First, it is desirable to use electrode assemblies that do not have rigid outer sleeves or do not have sleeves along their entire lead because they allow for greater design options in the means of bringing electrosurgical power from a power cord to the electrode at its proximal end. However, the use of an electrode assembly having a flexible lead requires the use of a working element having an electrode sheath with a substantially enclosed tube. Because fluids and other materials can enter the electrode sheath at its open distal end and, because the proximal end is sealed to prevent leakage external of the resectoscope, fluid between the electrode sheath and the electrode assembly can cause drag or hinder the movement of the electrode assembly because of such factors as fluid friction and the incompressability of fluids in the electrode sheath; the proximal end of the electrode sheath being substantially sealed.
Another problem arises in the devices known in the prior art in that the movement of the guide block on the guide bar of the working element, and thus the movement of the electrode assembly, can be hindered by accumulations of fluids or debris on the guide bar.
Fluid from a resectoscope operation can exit the resectoscope, especially when the working element is removed to use an evacuator, and lodge on the guide bars which can at least partially dry and form a sticky barrier to the smooth movement of the guide block on the guide bar. Because of the delicacy involved with resectoscope operations it is desirous to provide a smooth sliding guide block. Dried fluids or debris that come between the guide block and guide bar can cause drag or hinder this smooth movement.
It is therefore an objective of the present invention to provide a working element with an electrode sheath that can support an electrode assembly with a flexible lead and also allow fluids to exit the sheath and thereby substantially prevent fluid friction or pressure caused by movement of the electrode assembly relative to the electrode sheath from hindering the movement of the electrode assembly.
It is another objective of the present invention to provide a working element with a guide block that will not have its smooth movement substantially hindered because of liquids or deposits on the guide bar or between the guide bar and guide block.